imu: don't forward imu errors into mpy

components/flow3r_bsp/flow3r_bsp_imu.h

@@ -14,6 +14,15 @@ typedef struct {
     uint8_t dev_addr;
 } flow3r_bsp_imu_t;
 
+// Init the IMU to default settings
+//
+// 100 Hz sample rate, 2 g range
 esp_err_t flow3r_bsp_imu_init(flow3r_bsp_imu_t *imu);
+
+// Query the IMU for an accelerometer reading.
+//
+// This directly calls the I2C bus and need to lock the bus for that.
+// Returns ESP_ERR_NOT_FOUND if there is no new reading available.
+// Return values in m/s.
 esp_err_t flow3r_bsp_imu_read_acc_mps(flow3r_bsp_imu_t *imu, float *x, float *y,
                                       float *z);

components/micropython/usermodule/mp_imu.c

@@ -4,20 +4,14 @@
 #include "py/runtime.h"
 
 STATIC mp_obj_t mp_imu_acc_read(void) {
-    float x, y, z;
+    static float x, y, z;
 
-    esp_err_t ret = st3m_imu_read_acc_mps(&x, &y, &z);
+    // Will not overwrite old data if there is an error
+    st3m_imu_read_acc_mps(&x, &y, &z);
 
-    if (ret == ESP_OK) {
-        mp_obj_t items[3] = { mp_obj_new_float(x), mp_obj_new_float(y),
-                              mp_obj_new_float(z) };
-        return mp_obj_new_tuple(3, items);
-    } else if (ret == ESP_ERR_NOT_FOUND) {
-        return mp_const_none;
-    }
-
-    // TODO: raise exception here
-    return mp_const_none;
+    mp_obj_t items[3] = { mp_obj_new_float(x), mp_obj_new_float(y),
+                          mp_obj_new_float(z) };
+    return mp_obj_new_tuple(3, items);
 }
 
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(mp_imu_acc_read_obj, mp_imu_acc_read);